I started out with the 35mm MED rings on an Arms mount on a M1A rifle.The MED. gave me 7/16 inch clearance up front and 1/2 inch clearance on top of the rear sight. Put the LOW on to get closer to the rifle. The LOW was ok up front, but was resting on the rear sight. I will put the LOW on a Sadlak Airborne mount. The steel rings are cut 70/30 so they might look out of spec. But they fit perfect.